Let me start off by saying Robin apparently has just about the most overpowered ability in one piece and has the potential to be stronger than luffy if only if she bothered....
Let's start off by stating her df ability:the ability to bloom parts of her body anywhere in other words the hana hana no mi.
Now let's look at what she could do right now...
bloom thousands of body parts
bloom gigantic body parts
and she could recognize haki meaning she atleasty knows about it and knows what it can do
Give her rokushiki now what do you have?
someone that could bloom a hundred or so inescapable shigans on your body.
Someone who could throw a rankyakus(LOTS and LOTS of 'em) at you from just about anywhere on the ground not to mention she could hold you down by sprouting arms on the ground and grabbing.
someone who could move at the speed of any rokushiki master using soru
someone who could create a wall to block any attacks combining tekkai and haki(she'd need to learn this sometime troughout the series)
someone who could place inescapable rokougans on your body dealing massive damage
and to top it off she can clone herself and fly...